SARS-CoV-2 is a novel coronavirus, not encountered before by humans. The wide spectrum of clinical expression of SARS-CoV-2 illness suggests that individual immune responses to SARS-CoV-2 play a crucial role in determining the clinical course after first infection. Immunological studies have focused on patients with moderate to severe disease, demonstrating excessive inflammation in tissues and organ damage. In order to understand the basis of the protective immune response in COVID-19, we performed a longitudinal follow-up, flow-cytometric and serological analysis of innate and adaptive immunity in 64 adults with a spectrum of clinical presentations: 28 healthy SARS-CoV-2-negative contacts of COVID-19 cases; 20 asymptomatic SARS-CoV-2-infected cases; eight patients with Mild COVID-19 disease and eight cases of Severe COVID-19 disease. Our data show that high frequency of NK cells and early and transient increase of specific IgA, IgM and, to a lower extent, IgG are associated with asymptomatic SARS-CoV-2 infection. By contrast, monocyte expansion and high and persistent levels of IgA and IgG, produced relatively late in the course of the infection, characterize severe disease. Modest increase of monocytes and different kinetics of antibodies are detected in mild COVID-19. The importance of innate NK cells and the short-lived antibody response of asymptomatic individuals and patients with mild disease suggest that only severe COVID-19 may result in protective memory established by the adaptive immune response.

Nonalcoholic fatty liver disease (NAFLD) is a multifactorial condition, ranging from simple steatosis to nonalcoholic steatohepatitis (NASH) with or without fibrosis. NAFLD affects both adults and children who present with particular risk factors, including obesity, sedentary lifestyle and/or a predisposing genetic background. The escalation of the prevalence of NAFLD in children worldwide is a worrying phenomenon because this disease is closely associated with the development of both cirrhosis and cardiometabolic syndrome in adulthood. The etiopathogenesis of primary NAFLD in children is unknown; however, considerable knowledge about the mechanisms of liver damage that occur during disease progression has been gathered over the past 30 years. Understanding the pathogenetic mechanisms, together with the histological pattern, provide the basis to characterize potential early predictors of the disease, suitable noninvasive diagnostic tools and design novel specific treatments and possible management strategies. Despite a few clinical trials on the use of antioxidants combined with lifestyle intervention for NAFLD that showed encouraging results, to date, no treatment guidelines exist for children with NAFLD. In this Review, we provide an overview of current concepts in epidemiology, histological features, etiopathogenesis, diagnosis and treatment of NAFLD in children and adolescents.

BackgroundThere are no licensed treatments for non alcoholic fatty liver disease (NAFLD) in adults or children. In NAFLD, several studies have shown a benefit of omega-3 fatty acid treatment on lipid profile, insulin-sensitivity and hepatic steatosis and it has also been suggested that Vitamin D treatment has potential antifibrotic properties in liver disease.Trial DesignTo date, however, there are no studies that have tested the combination of Docosahexanoic acid (DHA) and vitamin D treatment which may benefit the whole spectrum of disease in NAFLD. Our aim therefore, was to test the effect of daily DHA (500 mg) plus vitamin D (800 IU) treatment, in obese children with biopsy-proven NAFLD and vitamin D deficiency, in a randomized, double-blind placebo-controlled trial.MethodsThe 41/43 patients completed the study (18-treatment, 23-placebo). At 12 months: i) the main outcome was liver histology improvement, defined by NAS; ii) the secondary outcome was amelioration of metabolic parameters.ResultsDHA plus vitamin D treatment reduced the NAFLD Activity Score (NAS), in the treatment group (5.4 v1.92; p<0.001 for baseline versus end of study). There was no change in fibrosis score, but a reduction of the activation of hepatic stellate cells (HSC) and fibrillar collagen content was noted (3.51±1.66 v. 1.59±1.37; p = 0.003) in treatment group. Moreover, the triglycerides (174.5 vs. 102.15 mg/dl), ALT (40.25 vs. 24.5 UI/l) and HOMA-IR (4.59 vs. 3.42) were all decreased with treatment.ConclusionDHA plus vitamin D treatment improved insulin-resistance, lipid profile, ALT and NAS. There was also decreased HSC activation and collagen content with treatment.

Breakthrough SARS-CoV-2 infections in fully vaccinated individuals are considered a consequence of waning immunity. Serum antibodies represent the most measurable outcome of vaccine-induced B cell memory. When antibodies decline, memory B cells are expected to persist and perform their function, preventing clinical disease. We investigated whether BNT162b2 mRNA vaccine induces durable and functional B cell memory in vivo against SARS-CoV-2 3, 6, and 9 months after the second dose in a cohort of health care workers (HCWs). While we observed physiological decline of SARS-CoV-2-specific antibodies, memory B cells persist and increase until 9 months after immunization. HCWs with breakthrough infections had no signs of waning immunity. In 3–4 days, memory B cells responded to SARS-CoV-2 infection by producing high levels of specific antibodies in the serum and anti-Spike IgA in the saliva. Antibodies to the viral nucleoprotein were produced with the slow kinetics typical of the response to a novel antigen.